1. Field of the Invention
This invention relates to apparatus for the external fixation of fractured bones, and, more particularly, to such apparatus having means for adjustably mounting and clamping a number of bone pins to a housing.
2. Summary of the Background Art
External fixation often provides the best method for holding bone fragments in place during he healing of a severe bone fracture, in which multiple bone fragments are formed. In the external fixation process, bone pins or wires ate surgically attached to the individual bone fragments and to intact sections of bone, so that a desired alignment of multiple fragments can be maintained during the healing process. The individual bone pins or wires are also attached to a frame that is external to the body to be held in a fixed configuration. Then, after the bone fragments have joined to one another in a satisfactory manner, the bone pins or wires are removed from the bones and from the body in another surgical procedure. With external fixation, an ability to hold individual bone fragments in place often makes in possible to achieve results that cannot be achieved using other conventional techniques, such as casting.
Since serious bone fractures can occur in many different ways in various parts of the body, forming various configuration of bone fragments, it is highly desirable that a device for external fixation should be configured in a variety of different ways, reducing the number of different types of fixation devices that need to be held in inventory to meet expected demands. To this end, the patent literature includes a number of descriptions of fixation devices that can be assembled from multiple elements in various ways or that can be adjusted to provide various configurational features.
One method to obtain this kind of flexibility has been to provide a plate having a number of holes defining locations in which bone pins or wires may be clamped, with only a variable subset of the holes being used in the treatment of a typical fracture. For example, U.S. Pat. No. 7,153,303 describes a fixture including several holes for clamping members to hold bone pins disposed within an elongated portion and a number of holes in a rectangular pattern, which can accommodate a variety of pin configurations. Such an arrangement is used, for example, to fasten the elongated portion of the fixture to the shaft of the radius bone within the arm and to attach various fragments within a broken wrist to a pattern of pins clamped within the rectangular array. A configuration for applying external fixation to a fractured tibia is also described as including a frame an elongated lower section for fastening the frame to the shaft of the tibia using bone pins extending along a straight line and an arcuate section extending from each side of the upper end of the elongated lower section for clamping bone pins extending into bone fragments within the upper portion of the tibia. U.S. Pat. No. 5,779,703 describes a bone organizer having a number of holes through which wires are attached to bone fragments.
Another method for obtaining flexibility within an external fixation device is to provide a number of clamping elements holding one or more bone pins, with the clamping elements being attached to one another by devices providing for pivotal adjustment. For example, U.S. Pat. No. 5,624,440 describes a fixture including a number of clamping elements, each of which clamps a pair of bone pins extending parallel to one another and a rod to which the clamping elements are attached by means of a pair of pivoting clamps providing for rotational adjustment and clamping about two axes perpendicular to one another. U.S. Pat. No. RE34,985 describes a fixation device having a pair of elongated carriers, each of which supports a pair of bone screws that are movable along the carrier by rotating a spindle. The carriers are joined to one another by a connector including a rigid rod and a ball at each end. The balls are received by partly spherical sockets that can be fixed relative to the balls through screws. U.S. Pat. No. 4,554,915 describes an external fixation frame including a fixation block from which one or more arms extend, with a ball and socket joint connecting each arm to the block for universal movement thereabout. Setscrews are provided for tightening the ball and socket joints. International Pat. Appl. Pub. No. WO 91/111 describes a fixation device having a pair of clamping members, each of which includes a row of holes into which bone pins may be inserted and clamped, with the clamping members being connected by a tube, into which a rod extends from one of the clamping members, while a ball from the other connecting member extends into a partially spherical hole within the tube. Setscrews are provided for clamping the rod and ball in place within the tube.
What is needed is a bone fixation device having the flexibility of adjusting the angle at which individual bone pins extend from a housing or frame, preferably with such an adjustment being provided through a clamping device that simultaneously clamps both the linear extension of the bone pin, along its length, and its angle relative to the housing or frame.
The fracture of the distal radius is one of the most common human fractures, occurring in as many as 350,000 people per year in the United States alone. The conventional processes both for reducing such a fracture and for maintaining the bones in proper alignment during the subsequent healing process involves applying and maintaining an extension force across the fracture, with ligamental taxis being relied upon to hold the bones in place. The process for treating a fractured distal radius is described in the 1901 edition of Gray's Anatomy in the following manner, “The treatment consists of flexing the forearm, and making a powerful extension from the wrist and elbow, depressing at the same time the radial side of the hand, and retaining the parts in that position by well padded pistol shaped splints.”
A common method for the treatment of a fractured distal radius involves the use of standard immobilizing cast techniques, preventing movement of the radiocarpal joint throughout the course of rehabilitation. A problem with this method is that it sometimes results in inadequate internal fixation, which can cause deformity, pain, and prolonged disability.
The process of external pin fixation is often used in the repair of a fractured distal radius. This process initially involves the surgical insertion of skeletal traction pins on both sides of the fracture, with a frame being connected to the pins for immobilizing the bones, and for holding them together until the fracture is mended. Conventional methods for applying external pin fixation for the treatment of a fractured distal radius provide for the immobilization of the radiocarpal joint, so that the hand cannot be flexed.
Examples of frames used in this way are found in U.S. Pat. Nos. 4,554,915 and 5,545,162. Each of these frames rigidly but adjustably connects a pair of pins extending into the metacarpal bones with a pair of pins extending into the radius on the proximal side of the fracture. While this type of fixation often provides an improvement over conventional casting techniques in the management of severe fractures of the distal radius, immobilization of the radiocarpal joint during the treatment period typically results in a long period of stiffness and disability after the external fixation device is removed. Typically the external fixation device is left in place during the healing process for six to eight weeks. After the fixation device is removed, three to six months are required for the patient to regain motion of his hand. Thus, what is needed is a fixation device providing adequate fixation during the healing process while allowing flexure in the radiocarpal joint of a fractured distal radius may alternately be repaired using a permanently installed fixation plate with screws and blades extending into the radius and into the broken fragments. The fracture of the distal radius is one of the most common human fractures, occurring in as many as 350,000 people per year in the United States alone. The conventional processes both for reducing such a fracture and for maintaining the bones in proper alignment during the subsequent healing process involves applying and maintaining an extension force across the fracture, with ligamental taxis being relied upon to hold the bones in place. The process for treating a fractured distal radius is described in the 1901 edition of Gray's Anatomy in the following manner, “The treatment consists of flexing the forearm, and making a powerful extension from the wrist and elbow, depressing at the same time the radial side of the hand, and retaining the parts in that position by well padded pistol-shaped splints.”
One method for the treatment of a fractured distal radius involves the use of standard immobilizing cast techniques, preventing movement of the radiocarpal joint throughout the course of rehabilitation. A problem with this method is that it sometimes results in inadequate internal fixation, which can cause deformity, pain, and prolonged disability.
The process of external pin fixation is often used in the repair of a fractured distal radius. This process initially involves the surgical insertion of skeletal traction pins on both sides of the fracture, with a frame being connected to the pins for immobilizing the bones, and for holding them together until the fracture is mended. Conventional methods for applying external pin fixation for the treatment of a fractured distal radius provide for the immobilization of the radiocarpal joint, so that the hand cannot be flexed. Examples of frames used in this way are found in U.S. Pat. Nos. 4,554,915 and 5,545,162. Each of these frames rigidly but adjustably connects a pair of pins extending into the metacarpal bones with a pair of pins extending into the radius on the proximal side of the fracture. While this type of fixation often provides an improvement over conventional casting techniques in the management of severe fractures of the distal radius, immobilization of the radiocarpal joint during the treatment period typically results in a long period of stiffness and disability after the external fixation device is removed. Typically the external fixation device is left in place during the healing process for six to eight weeks. After the fixation device is removed, three to six months are required for the patient to regain motion of his hand. Thus, what is needed is a fixation device providing adequate fixation during the healing process while allowing flexure in the radiocarpal joint.
While this type of fixation often provides an improvement over conventional casting techniques in the management of severe fractures of the distal radius, immobilization of the radiocarpal joint during the treatment period typically results in a long period of stiffness and disability after the external fixation device is removed. Typically, the external fixation device is left in place during the healing process for six to eight weeks. After the fixation device is removed, three to six months are required for the patient to regain motion of his hand.
An example of a fixation device providing adequate fixation during the healing process while allowing flexure in the radiocarpal joint is described in U.S. Pat. No. 6,197,027, the disclosure of which is incorporated herein by reference. This fixation device includes a number of pins clamped within pin mounting holes. Each pin extends through a flexible sleeve and through a clamping nut. Each pin-mounting hole includes a pilot hole guiding the pin and an internally threaded portion engaging an externally threaded portion of the clamping nut. As the clamping nut is tightened, the flexible sleeve is longitudinally compressed, so that it expands transversely to clamp itself within the pin-mounting hole and to clamp the pin within itself. The fixation device, which is configured particularly for external fixation of a fractured distal radius, includes a first number of such pins configured for attachment within a shaft portion of the radius and a second number of such pins configured to attachment to one or more fragments of the fractured radius. The fixation device also includes a sliding attachment block supporting a number of pins extending for lateral attachment to such a fragment.
However, in the holes used in the device of U.S. Pat. No. 6,197,027 to mount pins within the first number of pins, what is needed is a somewhat more simple, and therefore cost-effective, method for holding the pins in place. Such a method would preferably eliminate the need for the flexible sleeves to translate longitudinal compression into transverse clamping forces. In the holes used to mount pins within the second number of pins, what is needed is a more simple method, which will preferably clamp all of the pins in use simultaneously. Two or more of these pins may be used to clamp a single bone fragment in two or more places, or several pins may be used to clamp several bone fragments. Furthermore, since the process of setting a distal radius fracture typically includes an application of extension to the distal fragment(s), what is needed is a feature simplifying the application of such extension forces as the fixation device is installed on the fractured radius.
U.S. Pat. No. 5,545,162 describes a bone fixator including a proximal pin mounting block and a distal pin connected by a medial assembly, which connects the pin mounting blocks in a manner which is pivotally adjustable, and which further allows for adjustment of the distance between the pin mounting blocks. However, what is needed is a fixture for facilitating this distance adjustment so that it can be retained and gradually increased, instead of being lost when a clamping screw is loosened to allow movement. Furthermore, the method of U.S. Pat. No. 5,545,162 does not include the installation of pins within the fragments of bone; instead pins from the distal pin mounting block extend into the finger bones, adding a requirement that the extension forces must be directed through the wrist. To provide mobility of the hand and wrist, the fixture is pivoted with a ball joint. What is needed is a fixture rigidly holding pins extending into the bone fragments instead of into the bones of the fingers. Such a fixture would have advantages of holding different configurations of fragments in place, of holding them more rigidly, and of providing greater freedom of wrist movement.
U.S. Pat. No. 6,585,736 describes a fixture configured to provide external fixation of a fractured distal radius by including a first number of bolts for pins extending downward from the fixture into one or more bone fragments and a second number of holes for pins extending downward from the fixture into the shank, of the radius. The fixture also includes a sliding block through which rods extend to hold pins directed laterally into the fragment(s). A sliding plate including a number of holes aligned with the first number of holes is moved by a pair of setscrews to clamp the pins extending through the first number of holes. The second number of holes includes a hole within a sliding structure allowing a single pin to be moved with a fixture to provide extension between the fragments and the shank of the radius. What is needed is a method for adjusting the angular relationships between certain individual pins in such a fixture and a more simple method to hold pins directed laterally into the bone fragment(s).